Adjustment structure of a seat of a chair

ABSTRACT

An adjustment mechanism of a seat of a chair includes a frame secured to a bottom thereof, a base secured to a leg of the chair, and a lever used for locking the frame; the frame has rails, which have holding rooms therein; the base has left and right support portions respectively held in the rails so that the frame is displaceable relative to the base; the first support portion has spaced gaps formed along it; the lever is pivoted to the frame, and has an engaging end passed through a passage of the frame; the lever is biased towards a locking position by a spring, in which position the engaging end engages one of the gaps; thus, the seat can be forwards and rearwards displaced relative to the leg to change position for suiting people of different thigh lengths after the lever has been pivoted away from the locking position.

BACKGROUND OF THE INVENTION

1. Field of the invention

The present invention relates to a seat of a chair, more particularly one, which is can be horizontally displaced relative to a support leg of the chair to change position for suiting people of different thigh lengths.

2. Brief Description of the Prior Art

In order for people to sit more comfortably, there are various adjustable chairs made available, including those with angularly adjustable backs, and up and down adjustable seats. In light of the fact that thighs of people of different body heights will project forwards from the front of a seat for different distance, and that the relative position between the body gravitational center of a sitter and the leg of a chair will partially depend on the sitter's thigh length, it would be desirable that a seat of a chair can move horizontally relative to the leg to change position for suiting people of different thigh lengths. However, most currently available chairs are structured such that tops of the legs will face certain fixed portions of the seats after the chairs are assembled; in other words, the seats can't be horizontally displaced relative to the legs to change position. And, people might have to change their sitting posture according to the relative position between the seat and the leg of the chair they are seated on. Consequently, they are likely to have sore legs and waists, and have bad blood circulation.

SUMMARY

It is a main object of the present invention to provide an adjustment mechanism of a seat of a chair to overcome the above disadvantages.

The adjustment mechanism includes a frame secured to a bottom thereof, a base secured to a leg of the chair, and a lever used for locking the frame. The frame has rails, which have holding rooms along them. The base has left and right support portions respectively held in the rails so that the frame is displaceable relative to the base. The first support portion has spaced gaps formed along it. The lever is pivoted to the frame, and has an engaging end passed through a passage of the frame. The lever is further biased towards a locking position by a spring, in which position the engaging end engages one of the gaps. Thus, after the lever has been pivoted away from the locking position, the seat can be forwards and rearwards displaced relative to the leg to change position for suiting people of different thigh lengths, and for providing more comfortableness.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be better understood by referring to the accompanying drawings, wherein:

FIG. 1 is a side view of the chair according to the present invention,

FIG. 2 is an exploded perspective view of the adjustment structure according to the present invention,

FIG. 3 is a partial front view of the chair of the present invention,

FIG. 4 is a partial vertical section of the adjustment structure of the present invention,

FIG. 5 is a bottom view of the present adjustment structure,

FIG. 6 is a view of the present adjustment structure in action,

FIG. 7 is a side view of another chair equipped with the adjustment structure of the present invention, and

FIG. 8 is an exploded perspective view of the second embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIGS. 1 and 2, a preferred embodiment of a chair in the present invention includes a seat 1, a leg 2, and an adjustment mechanism 3. The leg 2 is of the type that are usually used with office chairs, and equipped with air pressure mechanism (not shown) to be adjustable in height.

The adjustment mechanism 3 includes a bottom frame 31 secured to a bottom of the seat 1, and a support base 32 securely joined to an upper end of the leg 2. The bottom frame 31 has a through hole 310, rails 311 on left and right sides thereof, which have holding rooms formed along them, and facing each other. The left rail 311 has a passage 312 on a vertical side thereof, and two ear-shaped projections 313 secured on the vertical side, each of which has a through hole 314. A lever 315 is passed through the through holes 314 of the ear-shaped projections 313 at a middle portion thereof, and has a handle portion projecting outwardly of the bottom frame 31, and an engaging portion 316 passed through the passage 312 of the bottom frame 31. In addition, an elastic element 317 is positioned around the middle portion of the lever 315, and connected with the engaging portion 316, and one of the ear-shaped projections 313 at two ends respectively; thus, the lever 315 is normally biased to a locking position where the handle portion thereof is directed substantially down. And, stopping blocks 318 are secured on front and rear ends of inner sides of the rails 311.

The support base 32 has a hole 320, left and right support portions 321, wheels 322 fitted on the support portions 321, and several spaced engaging gaps 323 on the left support portion 321. The diameter of the wheels 322 is substantially equal to the height of inner spaces of the rails 311. The support portions 321 of the support base 32 are respectively held in the left and the right rails 311 of the bottom frame 31 such that the bottom frame 31 and the seat 1 together can be forwards and rearwards displaced relative to both the support base 32 and the leg 2 while the bottom frame 31 is supported on the wheels 322, and such that the stopping blocks 318 prevent the bottom frame 31 from separating from the support base 32; when the lever 315 is biased to the locking position by the elastic element 317, as shown in FIG. 4, the engaging portion 316 of the lever 315 will engage one of the engaging gaps 323 of the support base 32, and in turns, the bottom frame 31 is secured in position; the engaging portion 316 will disengage the gaps 323, and the bottom frame 31 is displaceable relative to the support base 32 as soon as the lever 315 is pivoted away from the locking position by means of moving the handle portion thereof upwards, as shown in FIG. 3. Consequently, the seat 1 can be adjusted in position by means of displacing the bottom frame 31 relative to the support base 32 after the lever 315 is disengaged from the gaps 323.

In assembly, first the lever 315 is pivoted, and kept away from the locking position, and the bottom frame 31 is fitted onto the support base 32 with the wheels 322 being held in the rails 311 thereof. Then, the lever 315 is released for the engaging portion 316 to engage one of the gaps 323 to secure the bottom frame 31 to the support base 32, as shown in FIG. 4, and the stopping blocks 318 are securely fitted on the inner sides of the rails 311.

Not only can the present adjustment mechanism be used with an office chair whose leg is equipped with air pressure mechanism to be adjustable in height. Referring to FIG. 7, a short chair, which is equipped with a rotary support leg 4 so as to be changeable in direction, can also be equipped with the present adjustment mechanism.

Referring to FIG. 8, the support base 32 is further formed with touching projections 324 near to the wheels 322 on the support portions 321 thereof such that when the bottom frame 31 is displaced relative to the support base 32, frictional resistance to the rails 311 will be formed by means of the touching projections 324, and the seat 1 won't move too fast in adjustment.

In addition, an elastic element 33 is connected with the hole 310 of the bottom frame 31, and the hole 320 of the support base 32 at two ends thereof respectively; thus, in adjusting position, the seat 1 can be more easily displaced from those positions that are closer to the frontmost position or the rearmost one with the help of the elastic element 33.

From the above description, it can be easily understood that the seat of the present invention has advantages as followings:

1. Thighs of people of different body heights will project forwards from the front of the seat for different lengths, and the relative position between the body gravitational center of a sitter and the leg of a chair will partially depend on the sitter's thigh length therefore it is desirable that the relative position between the seat of a chair and the leg can be changed according to the sitters' needs. With the present adjustment mechanism, the seat can be forwards and backwards displaced relative to the leg to change position therefore it can suit people of different thigh lengths.

2. With the help of the elastic element 33, which is respectively connected with the bottom frame 31, and the support base 32 at two ends, the seat 1 can be more easily displaced from those positions closer to the frontmost position or the rearmost in position adjustment. 

1. An adjustment mechanism of a seat of a chair, comprising a bottom frame secured to a bottom of a seat of a chair; the bottom frame having first and second rails respectively on first and second lateral sides thereof, which rails have holding rooms therein; the first rail having a passage thereon, and a pair of ear-shaped projections near to the passage on an outward side thereof; each ear-shaped projection having a through hole; a support base securely joined to an upper end of a leg of the chair; the support base having first and second support portions on first and second lateral sides thereof; the first support portion having a plurality of spaced engaging gaps formed along it; the fist and the second support portions being respectively held in the fist and the second rails of the bottom frame and between the stopping blocks such that the bottom frame can be forwards and rearwards displaced relative to the support base; and a lever passed through the through holes of the ear-shaped projections at a middle portion thereof; the lever having a handle portion projecting outwardly of the bottom frame; the lever having an engaging portion passed through the passage of the bottom frame; the lever being biased towards a locking position by means of an elastic element, in which locking position the handle portion thereof is directed substantially down, and the engaging portion engages one of the engaging gaps of the support base; the elastic element being positioned around the middle portion of the lever, and connected with the engaging portion, and one of the ear-shaped projections at two ends respectively; whereby the seat can be forwards and rearwards displaced relative to the leg to change position together with the bottom frame after the lever is pivoted away from the locking position, and whereby the seat will be secured to the leg as soon as the lever is pivoted to the locking position to engage one of the engaging gaps.
 2. The adjustment mechanism as claimed in claim 1, wherein the support portions of the support base have a plurality of wheels fitted thereto, which contact inner sides of the rails of the bottom frame.
 3. The adjustment mechanism as claimed in claim 1, wherein the bottom frame has stopping blocks secured on front and rear ends of inner sides of the rails thereof, which can prevent the bottom frame from separating from the support base while the seat is displaced relative to the leg.
 4. The adjustment mechanism as claimed in claim 1, wherein a second elastic element is connected with the bottom frame, and the support base at two ends thereof respectively for helping the seat displaced in adjusting the seat.
 5. The adjustment mechanism as claimed in claim 2, wherein the support base is formed with touching projections near to the wheels on the support portions thereof, which can form frictional resistance to the rails while the bottom frame is being displaced relative to the support base. 